The present invention relates to a flat coreless motor with a tachogenerator, and more particularly to a mounting technique and a tachogenerator construction for incorporating the tachogenerator into the motor body.
Conventionally, it is difficult to incorporate a tachogenerator into a small-sized flat coreless motor because of its structure, so the tachogenerator is usually provided outside of the motor body by extending the rotor shaft of the motor out of the motor body. According to this technique, however, the thickness of the flat and thin motor increases due to the presence of the tachogenerator thereby making this technique disadvantageous.
Accordingly, it is an object of the present invention to eliminate the above noted drawbacks and to incorporate a tachogenerator into a motor body by incorporating a stator of the tachogenerator into a bearing holder of the motor shaft and by using a micro multi-polar tachogenerator rotor comprised of an anisotropic magnet and a pair of upper and lower rotor yokes made of soft magnetic material having plural comb-shaped poles.